iMac 2011 runs at half speed in OS X 10.6.8

[Eccofonic]

It has the i7 2600s cpu. I had copied a 10.6.8 install over from another machine using Disk Utility and when benchmarking the iMac with Geekbench, then comparing the results to everymac.com, the numbers are half of what they should be. Even Xbench shows it barely faster than a G5. This doesn't make sense. Looking at the Geekbench results, it's obvious it's using all 4 cores + HT.

Thanks to archive.org, I found a iMac12,x OS X 10.6.7 install image from May 2011. Managed to put it on a USB drive, booted off it and when it got to the installer program, I picked the Terminal instead... changed directory to the Applications folder on the internal hard drive and ran Xbench. Sure enough, the numbers were now more than double. Same with Geekbench.

I should also note that I booted OS X 10.9.5 off an external drive and achieved the same faster results.

Any of you Mac Gurus out there know what needs to be changed on the 10.6.8 install? A parameter file, adding/replacing some files from the USB drive?

I can only guess the CPU is crippled because a driver or a parameter file/setting is missing that's only on found the iMac12,x install disc/image... and not other discs.

I'd rather avoid having to wipe the drive and do a new installation.

Thanks for any advice...

 

[Amethyst1]

Sounds like the SpeedStep issue that plagued unofficial 10.6.8 on 2011 Mac minis.

Solution to that one: https://tinyapps.org/blog/202009070700_2011_mac_mini_snow_leopard.html

You probably have to copy over the plist files for your iMac's model ID rather than the mini's.

 

[Eccofonic]

Sounds like the SpeedStep issue that plagued unofficial 10.6.8 on 2011 Mac minis.

Solution to that one: https://tinyapps.org/blog/202009070700_2011_mac_mini_snow_leopard.html

You probably have to copy over the plist files for your iMac's model ID rather than the mini's.

Thanks, that page helped me figure it out.

I copied the iMac12_1.plist & iMac12_2.plist files from the iMac 10.6.7 image over and then opened a Terminal window and typed in the same stuff as the "script" except replacing the Macmini5* with iMac12* and ran the kextcache commands too. Note I didn't do anything else like copy over other .kext folders.

Rebooted and ran Xbench & Geekbench and... hooray! The iMac runs at full speed.

Thanks again for the tip!

 

[Eccofonic]

Thanks, that page helped me figure it out.

I copied the iMac12_1.plist & iMac12_2.plist files from the iMac 10.6.7 image over and then opened a Terminal window and typed in the same stuff as the "script" except replacing the Macmini5* with iMac12* and ran the kextcache commands too. Note I didn't do anything else like copy over other .kext folders.

Rebooted and ran Xbench & Geekbench and... hooray! The iMac runs at full speed.

Thanks again for the tip!

Whoops. Hit reply too many times...

But as long as this post exists, I'll also mention that most of my .kext folders were dated Feb 12, 2011... so maybe that's a clue as to which install disc I originally used.